pcb etching tip...

[MetalGod]

I'm sure most people here already know this, but I warmed up some Ferric Chloride before etching a pcb today and it etched MUCH quicker.

Less time in the etching solution means less chance of undercutting the image and it's nice and sharp too.

Even more of a surprise (for me) is how well magazine paper works in place of press-n-peel, it's actually alot better since the paper doesn't shrivel from the heat and the toner sticks much better.  I'm sold on magazine paper for transferring artwork onto PCBs now.

[The Tone God]

Etching speed doubles every 10 degrees C increase.

Andrew

[ambulancevoice]

WHOOO 10!

[markm]

Less time in the etching solution means less chance of undercutting the image and it's nice and sharp too.

Not neccessarily.
The FeCl is much more aggressive when it's warm therefore it is quicker but, it can get away from you faster as well meaning,
not as much control over the process.
I used to warm it for PCB etching but, not anymore.
Sometimes I leave the iron on next to the jar just to add a bit of heat.

[Paul Perry (Frostwave)]

If you use persulphate ( as I do ) you HAVE to warm it, or wait till summer....

[newfish]

So...

Knowing that I need to heat my etchant (FeCl) to something warmer than room temperature (current 'etchings' are taking 40 minutes, typically) - what's the safest way of doing this?

My Etchant solution currently lives in its bottle inside a bigger plastic bottle - to save spillage etc.

I've poured warm water into this outer bottle before now, and it *has* speeded up a little, but I'd like to be able to etch a small batch of boards in less than 40 minutes.

I've also used Darron's (I beleiev it's his...) excellent 'Spotlamp' idea over the etching tray.
Whilst it's true that the super low-watt eco-friendly bulbs are better for the environment etc, you really need an older (60 - 100w bulb) to get any sort of heat through.

Does anyone have a tried and tested method of warming the etchant though?

[Mark Hammer]

Ultimately, it is the etchant that is in direct contact with the copper surface that needs to be warm.  Obviously the best way of insuring this is to warm up the entire etchant bath, but there are other ways if full warming is awkward. 

If you have a small goose neck reading lamp that you can position over the back (component side) of the board while the copper side floats facing down, the radiant heat will be transmitted through the board and warm up the etchant adjacent to it.  When I get impatient or have a set of circumstances where there is risk of a sluggish and poor etch, these days I use my heat gun on the low setting, pointed at the component side that faces upwards while floating.  You can use a hair dryer too.

Since blowing air at the board with any force risk imbalancing it such that it risks sinking into the etchant, you can pop 4 little holes into the far corners of the board and fashion little "table legs" for it with toothpicks to make sure it remains steadfastly near the surface of the etchant.  Works like a charm.

[fogwolf]

I agree. Etching was always taking way longer for me than it seemed like it should. So recently I started warming it up in a tub of hot water for 5-10 minutes and then using a clamp-on lamp with hood and a 300W bulb as close as possible while etching. For a small board and using fresh (i.e. not previously used) Ferric Chloride it took less than 10 minutes.

[cheeb]

When I get impatient or have a set of circumstances where there is risk of a sluggish and poor etch, these days I use my heat gun on the low setting, pointed at the component side that faces upwards while floating.  You can use a hair dryer too.

I do this. I also etch in direct sunlight on a dark surface, and before placing the board in the etchant I heat it to scorching hot with a heat gun so that the heat will transfer to the etchant. Still takes forever. I can etch an enclosure in five minutes. A board feels like five hours. It's gotten to the point where I avoid building things on large boards just to avoid the etching process.

[newfish]

Maybe it's worth getting some of those Tupperware / sandwich box things of different sizes.

Use the box that fits your board size in, then you've got a much more controllable surface area for the cooling / heating to take a hold of.

I may well put the 'etch' box inside another - and put hot water in the outer box to at least *try* to speed things up.

I'm 33 and thinking of Tupperware.

I need to get out more I think...

[Monotremata]

Even more of a surprise (for me) is how well magazine paper works in place of press-n-peel, it's actually alot better since the paper doesn't shrivel from the heat and the toner sticks much better.  I'm sold on magazine paper for transferring artwork onto PCBs now.

Magazine paper?? Can you elaborate a bit more on this??? So instead of photocopying your circuit onto press-n-peel youre just using a page from a magazine??
How does it transfer to the PCB then?? Sorry if Im abit confused but Ive got a few sheets of unused copper plated stuff from Rat Shack Ive been holding onto for awhile because Ive just been too lazy (and havent had cash to get a big enough order to justify shipping costs) to get press-n-peel.
Hell if I can go cut up an old Rolling Stone or something laying around the house Ill probably have a few new circuit boards done by this weekend!

[eggman6]

Cant remember the site, was linked on the sloclone forum. But theres this company that sells its equivalent to pnp blue, looks alot better actually, even think they have something that can be used for silkscreening the boards.

Anyway, their recommended method for etching a board in minutes, is to soak a sponge in the ferric chloride, and then you use the sponge to "wash" off the copper, you don't need to understand the science to know why this will be quicker. And then to squeeze the sponge empty into a big container of water, which will be a very safe way to store the spent chemicals since its diluted a fair bit. and you also use very small amounts of enchant per board as well, apparently you will etch a board in a couple of minutes this way.


Due to the efficiency of this method i don,t see the point in any other way, but for those with trouble heating up their chemicals, why not just buy concentrate and preheat the water before adding it.

[stm]

The method described appears nothing more as a mechanical remotion of the copper-mixed chemical that forms on the board surface while etching.  This precludes stronger chemical from becoming in contact with the remaining copper surfaces.  For this very same purpose a soft paint brush can be used with equally good results.  In fact, in order to speed-up board etching (when I had the patience to do them at home) I gently tilted the container to one side and the other throughout the process, which caused a wave that helped cutting the etch time to around half (from 20 min to 10 min, in my case).

Another "technique" I came up with was a sort of lazyman implementation of the above: used a hair dryer fixed somehow in place so it served a dual purpose: heating the solution and at the same time creating waves that removed the dilluted chemical from the copper surface faster.  Worked very good, but I' strongly recommend wearing safety googles and using some newspaper to cover the board surface, as it is easy to have some spills if the hairdryer is not used carefully--after a second thought, you should use these safety measures anyway!

YMMV.

[eggman6]

I like the paintbrush idea more so than the sponge (keeps you even further away from that nasty stuff), those sponge brushes would probably be the best of both worlds. I generally cant be bothered with the whole etching though, all those spent chemicals, had the same problem developing film, i didn't plan what i was going to do with the chemicals, still got some got the bottles kicking about somewhere.

[newfish]

Thanks for the ideas folks.

Did a 'test etch' (simple booster board) last night in front of one of those plug-in heaters, and it *was* a little faster.
Heater had two bars, I used just one for the first 10 mins, then kicked in the second to see the difference - which was significant.
Etchant bottle was also sat in 70 degree (celcius) water for 5 mins beforehand too.

There was still some 'lift' in the traces though - so I'll be trying the Paintbrush method tonight.

Maybe, just ,maybe, I'll stop making boards long enough to play that stringed thing in the corner.
...what's it called again?